The snake - thought to be an American smooth-scaled racer - was found under a row of seats in the passenger cabin after the plane arrived from Mexico earlier this week, animal welfare charity Scottish SPA revealed.

Quick-thinking staff remained "remarkably calm" and managed to safely contain the 18in-long snake in a box, the charity said.

The juvenile reptile has been named Furtivo, because of his "sneaky" ways.

"We have had the snake examined by a vet and, although we can't be 100% certain, we believe he is of the Dryadophis family, which are commonly referred to as American smooth-scaled racers," said Scottish SPA's Billy Linton, a senior inspector with more than 30 years' experience as a zoo keeper.

"Racers aren't venomous but, like all snakes, they can bite and Furtivio is very feisty.

"Although small at the moment, he is still a juvenile and has a lot of growing to do.

"I can only imagine that Furtivo managed to sneak his way onto the plane while it was waiting to take off in Cancun, although it is also possible he has hitched a lift in someone's hand luggage.

"We have rescued several exotic creatures from international flights including scorpions, spiders, turtles and even giant land snails, so this isn't as unusual as many people might think.

"Furtivo will remain in our care until we can find him an expert home with someone who has the necessary experience and knowledge to be able to look after such a creature."